AB0052 CHANGES IN THE MOLECULAR ARCHITECTONICS OF PLASMA MEMBRANES (PM) OF NEUTROPHILIC LEUKOCYTES (NL) FROM SYNOVIAL FLUID (SF) IN GONARTHROSIS (GA)
Authors: V. Shishkin, Y. Malenkov, V. V. Shishkin, G. V. Kudryavtseva
Journal: Annals of the Rheumatic Diseases (2022)

Objectives Changes in the spectrum of phospholipids (PL) in NL membranes correlate with the activity of their metabolic and phagocytic processes. The aim of the work was to study PL homeostasis of NL from SF in GA. Methods SF of knee joints of 12 patients with GA with active synovitis and 7 conditional donors postmortem (D) were researched. PL analysis: рhosphatidylcholine (PC), sphingomyeline (SM), phosphatidylethanolamin (PEA), phosphatidylinositol (PI), phosphatidylserine (PS), lysophosphatidylcholine (LPC) were performed by conventional lipid-gas and fluid chromatography methods. Active forms of oxygen (AFO2) have been registered by applying EPR. Electrokinetic motility (EM) of NL determined by the automatic microscope. Results With GA, against the background of the sharp increase (2.7 times) of free radical processes, there are quantitative changes in the FL plasma membranes NL, expressed in the decreases in the percentages of PC, SM, PEA, PI and the increases in PS and LPS. Table 1. Phospholipids concentration (%), AFO2 (units/mg of protein) and EM (m/v sec) NL from SF in GA NL PC SM PEA PI PS LPС AFO2 EM D 25,8±0,9 18,7±0,3 27,3±0,7 19,7±0,4 9,5±0,9 5,1±0,2 21,7±4,9 1,20 ♦ 10-8 GA 20,4±0,7* 12,3±0,4* 11,7±0,6** 10,9±0,8** 13,2±0,4* 8,9±0,7* 59,4±7,5** 0,27 ♦ 10-8*** * - p &lt;0.05; ** - p &lt;0.01; *** - p &lt;0.001 A decrease in the level of PC and SM in GA indicates an increase in the sensitivity of NL membranes to reactive oxygen species and a decrease in their structural stability, an increase in microviscosity and fluidity. A decrease in the PEA level in GA is also associated with the sharp increase in the active forms of oxygen radicals, which leads to “loosening” of the membranes and the formation of hydrophilic pores. PI is an effector of many membrane enzyme-substrate complexes, and with GA, the percentage of PI is halved. An increase in the level of PS and LPC in GA indicate the presence of structural rearrangements and loosening of the hydrophobic region of the lipid layer of the NL membranes. The PEA / PS ratio in the control group was 2.87, and with GA - 0.89. This indicates a change in the saturation of the lipid bilayer of the NL membrane, an increases in microviscosity and fluidity. Quantitative shifts in the FL composition in NL membranes during GA lead to their pronounced depolarization and the 4.4 -fold decrease in EM. Conclusion FL form the NL apoptotic response, determine their plastic and energy potential. In GA, FL homeostasis of NL is disturbed and membrane-destructive processes development. Modification of the lipid bilayer of plasma membranes NL causes their depolarization, a decrease in plasticity, viscosity, electrical conductivity and EM. The noted changes in the molecular architectonics of NL membranes in GA inhibit their membrane-protective properties, antioxidant potential, and stimulate the apoptotic response. Disclosure of Interests None declared